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0xdeadbeef writes "Two weeks ago, MIT artist-in-residence Joe Davis used the Arecibo radio telescope to send a message to three stars in honor of the 35th anniversary of the famous Drake-Sagan transmission to M13 in 1974. It was apparently allowed but not endorsed by the director of the facility, and used a jury-rigged signal source on what will now be known as the 'coolest iPhone in the world.' The message encoded a DNA sequence, but no word yet on whether it disabled any alien shields. You can get the low-down on Centauri Dreams: Part 1, Part 2."

Pluto is a planet, it's just one of 5 dwarf planets. So yes, to be completely accurate, they'd either need to ditch Pluto or add Ceres, Haumea, Makemake, and Eris.

All that said, I'm guessing 'ET' woouldn't give two shits about the dwarf planets. He'd see the gas giants, and maybe our 4 inner planets. If they looked really close, they might see some assorted rocky and icy belts, but nothing worth mentioning compared to the other planets.

Of course, part of the idea of dwarf planets is to make them open ended, so you don't need to memorize all of them. The analogy is to mountains: there are lots of mountains, people don't memorize them all, but they're still given special recognition.

...No, really. We're still waiting for your reply. Seriously. So hurry up. Like, people are starting to think we're crazy, or on the fringe or something. Or just wrongmaybe. But we know you're real, right? So please, just say something. Ooh, wait! Id you're real and intelligent, don't say anything, then we'll know. OMG, LOL, thanx. Are you on Twitter?

Since ET already gets all our TV transmissions, plus cell phones and wifi, I don't think this one will make much difference.

Check out Radio Astronomy by Kraus. The end of one of the chapters discusses the relative signal strength of various earth transmissions. From memory, planetary radar was by far the strongest, the AM modulated video carrier of old fashioned analog UHF TV transmitters came in second (of course they're shut down now, and the "peak" from ATSC is not nearly as impressive).

Cell towers are actually pretty low power, your typical EMS land mobile is much more impressive (think of what you hear on a police scanner

Without any context --- e.g., our biochemistry, amino acid structure, nature of DNA --- this message amounts to about the worst practical joke in the history of interstellar communication. It has a relatively non-random structure, so clearly must mean something, and yet they'll never figure it out.

Without any context --- e.g., our biochemistry, amino acid structure, nature of DNA --- this message amounts to about the worst practical joke in the history of interstellar communication. It has a relatively non-random structure, so clearly must mean something, and yet they'll never figure it out.

But if they do figure it out, we'll get a message a century from now: "Delicious! Do you have any other recipes?"

>>But if they do figure it out, we'll get a message a century from now: "Delicious! Do you have any other recipes?"

Sadly, people rarely stop to wonder if the messages we're sending into outer space are a good idea. Aliens with a good grasp of game theory might just very well decide to drop a meteor onto any planet they find broadcasting into outer space. You know... just to be sure.

I actually find it sort of thoughtless that people like this are taking the entire fate of the world into their hands. Dramatic? Not so much, if you really stop to think about it.

Aliens with a good grasp of game theory might just very well decide to drop a meteor onto any planet they find broadcasting into outer space

If by 'good' you mean 'incredibly poor,' then yes. The response that game theory would dictate to that kind of attack would be a similar (or greater) response. The only way in which a near-C mass[1] attack would be a good plan would be if you could guarantee species annihilation in the first strike. Given that this signal is for starts 100ly away, you'd have to be able to guarantee that, within the next 100 years[2], we would not have any off-planet colonies that would be able to launch a counter attack.

You'd also have to make sure that there was no evidence of it that was observable from other star systems. The collision would be detectable a long way away, and you'd have to hope that no one else saw it and decided that the galaxy would be better off without a belligerent species like yours in it.

[2] It would have to be near-C or we'd see it coming and be able to intercept it, and also know who to shoot back at before it got here even if we couldn't destroy it in time.

[1] Assuming a straight-line projectile. In practice, you'd want to slingshot it around a different star to make it less obvious that you were the originator.

There's a good chance that this kind of biochemistry is universal; the universe is full of the kind of stuff that our DNA and proteins are made from, but we haven't observed a lot of other complex chemicals elsewhere.

Without any context --- e.g., our biochemistry, amino acid structure, nature of DNA --- this message amounts to about the worst practical joke in the history of interstellar communication.

But it is probably also the -best- practical joke in -our-history of interstellar communication. How many other interstellar practical jokes have we played?

It has a relatively non-random structure, so clearly must mean something, and yet they'll never figure it out.

It might just be a lack of imagination on my part, but I can't picture an organism evolving without some type of intrinsic code. If we got such a code, we'd probably realize that it was something similar to nucleotide sequences and that we didn't have all the tools to do anything with it.

The message is irrelevant, there's only so much they can learn from us even if they understand the message. What really matters is that they know we're there somewhere up in the sky.

What puzzles me is that we do it once every 35 years for a few minutes, yet the rest of the time we spend it carefully listening, as if aliens would do what we do not do, which is actively trying to communicate with them. They won't pick up a damn thing unless we beam it to them specifically, so if they're as dumb as us and on

Dear citizens of Centauri. I have a large sum of gold, 300 metric tons, I need to move off planet. If you'll deposit a small transfer fee, 3 metric tons of gold, in a local bank I will make arrangements to ship the gold to you. Signed crowned prince of Iowa.

Ok, I understand the "coolness" factor of radio transmissions to the stars, but in the end are they all wasted money? I mean, chances are another Hubble mixed with other probes can find where there is other life faster, quicker and easier than radio telescopes. We've been trying these for ages and they haven't picked up anything. So why not spend research money doing things that we know are going to work. Plus, its a whole lot more probable that we will find non-intelligent life throughout the universe than intelligent life. Even if we find life outside earth with the technology level of 1700s earth, they won't be picking up these signals and really for all but the last 100 years, humans wouldn't have been able to pick up this signal. So quit messing around with radio signals and find possible planets for life.

Another big problem is that for radio astronomy to work in finding alien signals, we must count on stability of civilizations on both ends to make it work, which history shows to be wishful thinking. If aliens do pick up this message and response, who's to say that by the time the response gets here we will have any resources at all to pick it up due to some war or other nonsense or having merely forgot or lost interest about such things over time. The same would seem to apply to the other end(s).
Also, man

Actually establishing communication is a secondary goal - just detecting incidental radio output of an alien civilisation would be a monumental discovery. That said, it does require both sides to have radio capability. So it's probably unlikely that we'll see anything if there are/were only a couple of other inhabited planets out there, but if instead the universe has a lot of life in it, we may get lucky and be in the right place and time to see *one*. If we aren't looking, then even that possibility is wa

Stars are immensely more powerful, generally point sources than radio telescopes. So while not optimal at all for long range transmission we can still see their image.(after quite a bit of work, knowing or at least suspecting what we are trying to resolve the image to)
So again, you are solely reliant on the antenna gain you get with a telescope array to be able to reliably transmit information over long distance, and this gain is only valid for free space or similar attenuation.

I hope its a waste of money, but there is a tiny chance it is a lot worse: something listening might actually be able to come here. Historically when the "guys on the ships" meet the "guys on the shore", the guys on the shore don't do very well. One could also make an argument that if you detect an alien culture, your best bet is to launch a relativistic bomb (or the information equivalent).

Sure, although on the other hand there's only so many ways we could be able to detect any eventual technological civilisation, so we might as well try them. I mean think about it, optical systems aren't yet able to resolve a body the size of Earth even if it was around a nearby star, and our probes might find basic life on Mars, in Europe or on Titan, but even if they do that'll be some microbiology crap. If there's some dudes (or super smart land-squids) out there in the sky who mastered electricity the on

Sending out a DNA sequence assumes that the receiver understands a great deal about our planet and the molecular basis of life on it.

Think about it, even if they understood the message was about DNA, they would have to know our amino acid code in order to interpret it as the template for a protein. A protein that either did not evolve on their world, or evolved in a completely different way.

In effect, all we saying with this message is that we have advanced enough to recognize that DNA is the basis for life on this planet. Only a sentience that already understood that basis could interpret this message.

It's akin to someone shouting, "a-squared + b-squared = c-squared!" - out-of-context - in the antarctic. It shows you have learned something, but there either isn't anyone to hear you or they won't understand you unless they knew all about you (and Euclidian geometry) already.

Even if we make the assumption of organic life, which isn't far-fetched given all of the awesome self-organizing things organic molecules (biotic or abiotic) can do, we have as yet no reason to assume that nucleic acids will be the information carrier in an alien life form. Even if we do assume that nucleic acids are the information carrier, we have no reason to assume that the genetic code is universal.

The evolution of the genetic code is perhaps the biggest mystery in the origins of life on Earth. We are

So if you're going to send a message, you have to choose one. What did he choose? The DNA sequence for an enzyme.

We used Apple's "Speak" option to vocalize the phonetic code which I then recorded on my iPhone. Here is a fragment of the total message, the whole of which can be decoded unambiguously into the gene for RuBisCo:

Tell me how, exactly, the recipient is going to decode a DNA sequence, even if the basic message can be identified as strings of 2-bit numbers? Not only is DNA specific (as far as we know) to Earth chemistry, but the meanings of the codons, and even the choice to interpret them in triplets is the result of chance evolution on this planet. It's like sending a message in Navajo to Paris, with the assumption that it can be "decoded unambigiously"... because the sender knew what it meant. The meanings of DNA codons are absolutely not a universal constant like binary math is.

[_] They're hoping the aliens will succumb to Steve Jobs Reality Distortion Field.
[_] At our nearest stellar neighbour, Soviet Centaurans serve YOU. (yum yum thx 4 gene seq bzzzt!)
[_] Your call is important to us. Please stay on the line. Your call is important to us. Please stay...
[_] What? Can you hear me now? What? Frakking Aldebaran Telephone and Telecommunications! Get me a Droid!
[_] Get the base ships ready to jump! We've found the 13th colony!
[_] Oh shit. Spaceballs! Oh well, there goes the galaxy...
[_] What, is your planet still there? The highway goes through next wee, you know!
[_] The.... answer.... is.... 42.... point.... (click) Your time is up. Please insert another 50 million galactic credits to call again.
[_] The borg collective are pissed off at how you've portrayed them. They'll be in your area soon to "discuss it." BTW, we're calling first dibs on your planet.
[_] Sorry, we don't want any illegal aliens in the neighborhood. Please go to another quadrant or we'll have to report you.
[_] Why did the zhicvben cross the whowde? To get to the other side! Thank you, thank you. I'm here all diurnal-periods-times-7. Try the phizch.
[_] That is the most odious and obscene collection of insults and violations of universal taboos any alien race has ever sent our way. Prepare to die, earth scum! We will be avenged!

Let's hope that either they're not there, or they can't hear us if they are, or if they can hear us, they can't reach us, because the odds are that what we'll have is a failure to communicate.

we can't even communicate properly between spouses - it's an incredible conceit to think we could get it right first time with an alien species, and not break any taboo, or accidently insult them... of that they'd be friendly.

Survival of the fittest means that the predators get to the top of the heap. Don't invite predators unless you *know* that you're better able to defend yourself than they are.

Not only is DNA specific (as far as we know) to Earth chemistry, but the meanings of the codons, and even the choice to interpret them in triplets is the result of chance evolution on this planet

We generally suspect this to be true but without other life to compare it to we can't be sure. The thing is there are serious biochemical constraints on what the codons can code for since the tRNA's (chemical structure is related to what amino acid it calls for. Since the tRNA's structure is determined in part by the structure of the messenger RNA which is determined solely by the DNA, there are constraints. They don't look that severe but we don't know.

Given that we didn't beam out the Wikipedia article for the first message, [wikipedia.org] I'm going to try and anticipate what the alien civilization will see it as by deciphering it myself without reading the article first:

"From top to bottom, the word 'aliens' in white English letters, a purple rock, some Space Invaders, a man with a giant blue head and a staff to his right, some white noise, and a bunch of stars over Planet GMail."

We have no idea if the receiver is friendly. Based on human behavior, we can roughly guess that at least 10% of any/all intelligent receivers will be agressive. Why broadcast our location with those odds? It's not logical.

Well, because we already broadcast enough, so sending yet another message does not really matter anymore. What I worry is our regular TV programming, which in the eyes of any advanced culture should make earth look like it's populated with some crazy monkeys flinging shit at each other.

Whether we imagine aliens to be friend of foe tells a lot about our own perception and mind set. And this perception changed dramatically over the decades up to a point where pop culture (or sci-fi too) overwhelmingly considers aliens to be a threat. It wasn't so earlier. How comes that?
Another point to ponder is this: if an alien culture were able to travel faster than light (and receive our signals before they arrived, but let's not be distracted by that), they would also be immensely more advanced than

It is logical if you take the position that WE are the agressive ones. Like you pointed out, broadcasting a signal is a sign of confidence - first it shows that we have the technology to do it (note the lack of signals being received from us - perhaps we're the most advanced!) and second that we have the interest to do it, and the confidence to deal with the consequences.

Based on human behavior, we can roughly guess that at least 10% of any/all intelligent receivers will be agressive.

Really want to mess with your head? Try this on for size. Based on human behavior, we can roughly guess that at least 90% of any/all intelligent receivers will believe in some form of supernatural friend in the sky whom runs the whole show. Now how are they going to freak out when a dude in the sky starts talking to them?

See, now slashdotters whom watch too much BSG are worried about fighting the cylons, but the average (and below average) moron on the street is going to be worried about the supernatural implications.

Hello! I am a creature from a galaxy far away, visiting your planet.I have transformed myself into this text file. As you are reading it, Iam having sex with your eyeballs. I know you like it because you aresmiling. Please pass me on to someone else because I'm really horny.

My Dear Friend and Earthling,
My name is Mr. Zebel Braumat, I am a senior priest in the highest order of our race. We are conducting a standard process investigation/Recommendation on behalf of all Advanced Common Civilization (ACC).
This investigation involves an ancient race who shares similar DNA as with yours from which we have previously received messages from. The circumstances which surrounding investments made by this race at ADB Gold Account, the Private Banking arm of ACC. The ACC Private Banking client died intestate and nominated no successor in title over the investments made with the bank amounting to over galactic 9.5 Gazillion dollars.
The essence of this communication with you is to request that you provide us information/comments on any or all of the four issues as regards nominating your race to inherit the fund left behind by this previous race. You are therefore being contacted to be legally nominated as next of kin(inheritor) to this race after all enquiries and investigation has yielded results showing that there is no known successors. You are required therefore to answer this questions to enable us make our recommendation.
1-Are you aware of any relative/relation born on the 2nd of February 1951, who shares your same name whose last known contact address was West Africa?
2-Are you aware of any investment of considerable value made by such a person at the Private Banking Division of ADB Bank PLC?
3-Can you confirm your willingness to accept this inheritance if you are legally and legitimately nominated and approved to stand as inheritor to this huge investment in regards to the bank account with ADB?
4-Would you agree to donate part of this inheritance to charity if you are officially approved to stand as the inheritor? It is pertinent that you inform us ASAP whether or not you are familiar with this personality or and your interest towards the issues mentioned.
You must appreciate that we are constrained from providing you with more detailed information at this point. Please respond to this mail as soon as possible to afford us the opportunity to provide you with more information on this investigation and recommendation.
Thank you for accommodating our enquiry.
Mr. Zebel Braumat
For: Advanced Common Civilization
Kappa Ceti (G5B)

We could never pick up a radio signal from an alien civilization because the power of a signal from a point source drops off exponentially..

Umm..... its not a "point source" its a spherical reflector..... the whole point of the construction of big antennas is to allow you to do precisely what it is you friend appears to believe is impossible.

Oddly, we just solved this problem in E&M class. If you had antennas with 80 dBi gain at both ends and a megawatt of power, that would be sufficient to transmit 10^5 bits per second over a lightyear gap with a received power level above the thermal noise floor (e.g. the antenna does enough work on the receiver to flip a bit). Raise the distance to 100 lightyears and reduce the gain to 73 dBi (e.g. Arecibo) and you lose 5.5 orders of magnitude in bit rate. Up the power to three megawatts (not hard to imagine) and you get back half an order of magnitude. So the achievable rate over 100ly using only current Earth technology at both ends is about a bit per second. Useless, perhaps, but not technically impossible.

The entire Wikipedia section on the production of titanium is a little under 4 kilobytes, which would take a bit over an hour to transmit at those rates. Imagine an alien species has a new ultra-efficient titanium refining process - would you wait a day to get the summary of it downloaded for your scientists? I sure as hell would.

The two-hundred-year transmission lag to go a hundred lightyears is a far bigger issue than the bandwidth.

The entire Wikipedia section on the production of titanium is a little under 4 kilobytes, which would take a bit over an hour to transmit at those rates. Imagine an alien species has a new ultra-efficient titanium refining process - would you wait a day to get the summary of it downloaded for your scientists? I sure as hell would.

In the science fiction story "Dragons Egg" by Robert L Forward [wikipedia.org] (who was incidentally a physics professor and described the book as "a textbook on neutron star physics disguised as

I'm not sure that giving knowledge away for free was really promoted there. The humans did give away knowledge, and in the end it worked out but for a time it started a lot of shit.

And then at the end of Dragon's Egg, the now-vastly-more-advanced aliens don't actually return the favour to the humans. Not directly, anyway: they leave the secrets in places that can only be accessed once the secret has already been discovered, basically so humans can check their work when they catch up.

On the other hand, it also only takes one civilization to construct self-replicating peacekeepers that could defend the galaxy at a significant fraction of the speed of light. And if those self-replicating terminators already exist, well, we're fucked as it is, so we may as well get it over with quickly.

I actually wouldn't be surprised if we are the first, or at least, the first with a good shot at reaching an interstellar society within our galaxy, simply based on the fact that any species that goes inters

Our star is in the second generation, so anyone around a first generation star had a head start of a few billion years. They'd have much more difficulty reaching space because they'd have a shortage of heavier elements (most of the ones we have access to come from the collapse of first-generation stars). With self-replicating colonies and a decent ion drive (i.e. stuff we could build with known science and just a bit of engineering effort if we had the political will), it would take around a million years to colonise the entire galaxy. Between the formation of the first planets in this galaxy and the formation of life on Earth there was enough time for a few thousand species to be born, create galaxy-spanning empires, and die out (or become non-corporeal, or go to a different universe, or whatever species do once they've conquered the entire galaxy).

It's also worth noting that the majority of stars in this galaxy are binaries. Life around single stars might be more rare. The tidal forces from the two stars on the crust of a planet in a binary system are likely to increase surface radioactivity and mutation rate, and intelligence would be much more of an advantage in the rapidly changing environment of a planet in an eccentric orbit. It's entirely possible that there are interstellar civilisations around most of the binary stars in the galaxy, completely ignoring us because life around single stars is so unlikely it's not worth investing effort searching for.

Depends. I'm imagining just sending the chemical formulas across. It wouldn't be all that hard to come up with a lingua franca for chemistry - it's not like hydrogen behaves differently on Alpha Centauri or anything.

Pin down the chemistry basics, get the essential formulas, then send "oh yeah and also titanium plus these chemicals equals this other set of chemicals, add electricity and you get this, then separate and you get this". At that point it's just down to an engineering challenge to figure out that

Considering that your transmission is going to take a hundred years to get there in the first place, 1 bit per second wouldn't be all that bad.

1 * 60 * 60 * 24 * 365 * 100 / 8 = a bit less than 400 megs enroute at any given time. So you could send them about half a cdrom before they even got the first bit, or about a wikipedia per decade. Of course if the deletionists get their way, we could probably send the wikipedia in about a month.

So the reason why noone has heard us, is not because noone is out there, but is because our technology for interstellar communication still sucks.Oddly enough that makes me feel much better about the chances of finding someone out there....eventually.

You have no idea about what you are talking about. It is true that omni directional radio sources are subject to inverse square law, but directional signals degrade less slowly. Scientists have calculated that using the Arecibo dish at one megawatt the signal could be received by a similarly sized dish 10000 lightyears away. I think I trust calculations done by people with PhDs in astronomy more than calculations done by you and your friend

This (and some previous, as well as some following) comments, have absolutely no clue whatsoever about E&M radiation. If you don't know, don't post.

The strength of electromagnetic radiation drops off as the square of distance. (As long as you're far enough away to ignore "near-field effects", which for the astronomical distances we are talking about, they can very well be ignored.)

It is always the square of the distance no matter what antenna geometry, gain, feed, or other technolog

But *why* is it still the square of the distance when I always thought that was just a natural consequence of the increase in volume of a sphere as it's radius increases? If antenna gain makes no difference, then why bother with it at all?

Not volume. Surface area. What is the amount of energy passing through some unit area in a unit of time. Google flux. For a sphere, the area increase as r^2. Double the distance and you have 1/4 the flux. The point of a big dish is to intercept more of the flux, and to get better angular resolution.

But *why* is it still the square of the distance when I always thought that was just a natural consequence of the increase in volume of a sphere as it's radius increases? If antenna gain makes no difference, then why bother with it at all?

Because although the covered area is much smaller, it still grows quadratically with distance (there simply is no such thing as an exactly parallel beam). The antenna makes a difference in that you get a higher signal in the desired direction to begin with. If your signal is e.g. 25 times as strong in a certain direction, it will remain 25 times as strong even after millions of lightyears. So at a distance where the weak signal would be barely detectable, you still have 25 times the threshold, which should

It is true that omni directional radio sources are subject to inverse square law, but directional signals degrade less slowly.

As it is a linear partial differential equation, all solutions to the wave equation and equations of its type are governed by what is known as the "fundamental solution" or "Green's function" of the equation. In the case of wave type equations(in 3 or more dimensions), this solution will be a delta function type solution which decreases inversely with distance from the source. Squaring its amplitude to obtain energy gives an inverse square energy decrease.

It must be stressed that all solutions of the wave equation, no matter what the sources, or boundary or initial conditions, must all be functions derived, more or less, from convolutions of the fundamental solution with the source terms. You cannot escape the inverse square behaviour of wave propagation over long distances with finite wave sources. The fundamental solution characterises all waves because of the linearity of the wave equation.

Now, there is a second fundamental solution for the wave equation; the so called "acausal" Green's function, which represents an inwardly collapsing wave, or by some conventions, a wave travelling backwards through time. Naturally, these waves are not considered in the context of the transmission of signals. Even if they were, these waves also display and inverse square relation for signal strength( going backwards in time of course).

This has been your daily mathematical public service announcement. Complaints to be directed to the Dean.

...right somebody has been reading too much pop-science and not nearly enough of the real thing.You can't construct a species with *just* DNA, that idea was popular in the 60's real geneticists have long since learned better.For starters, there are prions - which have a significant impact on how DNA is actually USED to make proteins, (same DNA, different prions - very different [and probably dead] result).And that's not the half of it. Did you know that frog DNA is several orders of magnitude more complex

Exactly. I don’t think the phone model would have been mentioned (and with a wink nonetheless) that way if it were another phone.

Besides: Even a iPhone that sent stuff to another planet and got a reply, can’t beat a Linux running Nokia N900 with built-in full root access, from a company whose phones had SSH terminal software available for more than seven years now. </proper-geek-fanboyism>;)

Definitely, sending the same message repeatedly is better than sending multiple messages in different encoding schemes. However:

The Arecibo message was designed to be as easy as possible to decode, it would be possible to do so with just a pencil and paper.

Designed, sure. I recall reading that it was nigh-impenetrable in practice, and it flip-flops between ways of encoding the same data at various points (e.g. it introduces a scheme for writing binary in limited space in the first part, then ditches it in f